The present invention relates to an electrically operated needle valve used for controlling the amount of flow of a refrigerant in a refrigerating circuit and to a refrigerating system provided with such an electrically operated needle valve.
Referring to FIG. 14, there is shown a construction of an electrically operated expansion valve Z0 which is used for controlling the amount of flow of a refrigerant in a refrigerating circuit. A concrete description of the construction of the prior art electrically operated expansion valve Z0 will be made below for providing a description of the present invention which will be set forth later.
In FIG. 14, the electrically operated expansion valve Z0 has a valve main body 1, a needle 2, and a casing 3. The valve main body 1 is formed into a different diameter body including a flow path formation portion 1a of larger diameter which is positioned on the side of one axial end of the valve main body 1, a screw thread formation portion 1c of smaller diameter which is positioned on the side of the other axial end of the valve main body 1, and a shoulder portion 1b of medium diameter which is positioned between the flow path formation portion 1a and the screw thread formation portion 1c. The shoulder portion 1b and the screw thread formation portion 1c are inserted into an internal space 30 of the casing 3 through an opening 33 formed in one end face of the casing 3. And, the valve main body 1 is made integral with the casing 3 with the shoulder portion 1b and the screw thread formation portion 1c inserted in the casing 3.
The flow path formation portion 1a of the valve main body 1 is provided with a refrigerant flow path 9. The refrigerant flow path 9 is composed of a refrigerant introduction portion 11 and a refrigerant withdrawal portion 12, these portions 11 and 12 being approximately orthogonal to each other. Formed at an opening edge of the refrigerant introduction portion 11 is a valve seat portion 15. A refrigerant introduction pipe 13 is connected to the refrigerant introduction portion 11, whereas a refrigerant withdrawal pipe 14 is connected to the refrigerant withdrawal portion 12.
A needle fit/insert aperture 16 having a given diameter is formed in the valve main body 1. The needle fit/insert aperture 16 is so formed as to extend from the refrigerant flow path 9 of the flow path formation portion 1a to an end of the screw thread formation portion 1c. And, one end of the needle fit/insert aperture 16 opens to the refrigerant flow path 9, whereas the other end of the needle fit/insert aperture 16 opens to an end face of the screw thread formation portion 1c. 
The needle 2 is slidably inserted into the needle fit/insert aperture 16. Formed at one end of the needle 2 is a valve head portion 20. The needle 2 travels back and forth along its axial direction, thereby increasing and decreasing the area of a passage between the valve head portion 20 and the valve seat portion 15. Because of such increase and decrease in path area, the amount of flow of a refrigerant flowing from the refrigerant introduction pipe 13 to the refrigerant withdrawal pipe 14 is controlled. Further, when the valve head portion 20 seats against the valve seat portion 15, the refrigerant flow path 9 is placed in the fully closed state. As a result, the circulation of the refrigerant is stopped.
The needle 2 is composed of a stepped shaft body including a sliding shaft portion 2a of larger diameter which is positioned on the side of the valve head portion 20 and a supporting shaft portion 2b of smaller diameter. And, the sliding shaft portion 2a is slidably supported by the valve main body 1 and the axial center position of the needle 2 is held. An extremely narrow needle fit/insertion clearance 17 is defined between the inner peripheral surface of the needle fit/insert aperture 16 and the sliding shaft portion 2a of the needle 2. Further, defined between the inner peripheral surface of the needle fit/insert aperture 16 and the supporting shaft portion 2b is an inner peripheral clearance 22 which is of larger clearance size than that of the needle fit/insert clearance 17.
On the other hand, a pressure equalization aperture 18 having a given diameter is formed in the shoulder portion 1b of the valve main body 1 so that the needle fit/insert aperture 16 passing through the axial center portion of the shoulder portion 1b and the lower end of the internal space 30 of the casing 3 communicate to each other. That is, by virtue of the formation of the pressure equalization aperture 18 of given diameter, the needle fit/insert clearance 17 and a first space portion 31 (which will be described later) communicate with each other.
Further, formed on the outer peripheral surface of the screw thread formation portion 1c of the valve main body 1 is an external thread. A rotor portion 10 constituting a part of an electrically operated means X is disposed on the diameterwise outside of the screw thread formation portion 1c. The electrically operated means X axially drives the needle 2 and is composed of a so-called stepping motor. The electrically operated means X has the rotor portion 10 and an electromagnet 5 disposed on the outer peripheral side of the casing 3.
The rotor portion 10 has a screw thread formation member 7 and a spacer 6. The screw thread formation member 7 is formed into a bottomed tubular-like shape. Formed on the inner peripheral surface of a peripheral wall portion 7a of the screw thread formation member 7 is an internal thread which meshes with the external thread of the screw thread formation portion 1c of the valve main body 1. The spacer 6 is formed into a tubular-like shape having collars at both ends thereof. A permanent magnet 4 is positioned on the outer peripheral side of the spacer 6. On the other hand, the peripheral wall portion 7a of the screw thread formation member 7 is force-fit in the inner peripheral side of the spacer 6 and fixed there rigidly.
The rotor portion 10 is inserted from above the screw thread formation portion 1c of the valve main body 1 with the screw thread formation member 7 engaging with the screw thread formation portion 1c so that the rotor portion 10 is attached to the valve main body 1. Accordingly, the rotor portion 10 rotates in correspondence to the amount of energization (pulse value) of the electromagnetic 5 and makes a relative movement in the axial direction of the screw thread formation portion 1c with respect to the screw thread formation portion 1c of the valve main body 1.
The needle 2 is connected to the rotor portion 10 so that the needle 2 is placed in the opened or closed state by the axial movement of the rotor 10. That is, the upper end of the needle 2 passes through an end face portion 7b of the screw thread formation member 7 and projects therefrom upwardly. The projecting end of the needle 2 is provided with a retaining member 34. The retaining member 34 prevents the needle 2 from slipping downwardly from the screw thread formation member 7. Further, a compression spring 35 is positioned between a step portion between the sliding shaft portion 2a and supporting shaft portion 2b of the needle 2 and the lower surface of the end face portion 7b of the screw thread formation member 7. The spring 35 constantly applies pressing force to the needle 2 and to the screw thread formation member 7 in the direction in which the retaining member 34 abuts against the end face portion 7b of the screw thread formation member 7.
Accordingly, in the range up to the time that the valve head portion 20 seats against the valve seat portion 15, the needle 2 travels with the axial movement of the rotor portion 10 for the increase or decrease in passage area. On the other hand, when the valve head portion 20 seats against the valve seat portion 15, further downward movement of the needle 2 is regulated. In this state, the rotor portion 10, while compressing the spring 35, downwardly travels just a given distance. And, the needle 2 is held in the closed valve state by energizing force of the spring 35. In this case, there is defined a given clearance between the retaining member 34 and the end face portion 7b of the screw thread formation member 7 (for example, see FIGS. 9 and 10 about embodiments of the present invention).
In order to adequately hold a magnet effect between the permanent magnet 4 and the electromagnet 5, the gap between the permanent magnet 4 and the inner peripheral surface of the casing 3 should be set extremely small by the rotor portion 10. Such a gap is for example about 0.2 mm. Therefore, the internal space 30 of the casing 3 is zoned by the rotor portion 10 into a first space portion 31 defined below the rotor portion 10 and a second space portion 32 defined above the rotor portion 10. The first and second space portions 31 and 32 communicate to each other through an outer peripheral clearance 21 defined between the outer peripheral surface of the permanent magnet 4 and the inner peripheral surface of the casing 3.
The prior art electrically operated expansion valve Z0 generally has the above-described structure.
When there is a rise in refrigerant pressure on the upstream side of the electrically operated expansion valve Z0 by compressor drive, the electrically operated expansion valve Z0 receives such a refrigerant pressure rise. As a result, there is produced a pressure differential in the inside of the electrically operated expansion valve Z0. Consequently, a part of the refrigerant flows into the internal space 30 of the casing 3 from the refrigerant flow path 9 through the needle fit/insert clearance 17.
That is, a part of the refrigerant flowing into the needle fit/insert clearance 17, after passing through the pressure equalization aperture 18 in communication with the needle fit/insert clearance 17, directly flows into the first space portion 31.
On the other hand, the remaining refrigerant flows upward through the needle fit/insert clearance 17. Further, the remaining refrigerant flows upward through the inner peripheral clearance 22 defined between a portion of the needle 2 located nearer to the other end thereof and the needle fit/insert aperture 16 of the valve main body 1 from the needle fit/insert clearance 17. Thereafter, the refrigerant is reversed and flows downward through an engagement portion clearance 23 defined between the screw thread formation portion 1c of the valve main body 1 and the screw thread formation member 7. Then, the refrigerant finally reaches to the first space portion 31.
These refrigerants, which have flowed into the first space portion 31 from the foregoing different two routes and merged together there, further flow upward through the outer peripheral clearance 21 and flow into the second space portion 32.
Such refrigerant flow into the first and second space portions 31 and 32 of the casing 3 cancels a difference in pressure between both the axial sides of the rotor portion 10. This ensures smooth movement of the rotor portion 10. In this state, the needle 2 moves with the movement of the rotor portion 10, whereby the amount of refrigerant flow is controlled.
On the other hand, when the compressor stops operating and refrigerant pressure on the upstream side of the electrically operated expansion valve Z0 decreases, a refrigerant in the internal space 30 of the casing 3 follows a route opposite to the above and is flowed back to the refrigerant flow path 9.
Incidentally, the temperature of a compressor sliding portion used in a refrigerating system becomes high under severe operating conditions due to metal contact. As a result, refrigerating machine oil and processing oil remaining in the circuit will undergo degradation, thereby giving rise to the generation of sludge of high viscosity. Besides, the sludge has the property of being refrigerant-insoluble or being difficult to be dissolved into a refrigerant, resulting in the generation of sludge which has not been dissolved into a refrigerant and remained separated therefrom. Such sludge thus generated circulates through the refrigerating circuit, together with the refrigerant.
In this case, with the compressor operation start and stop, in the electrically operated expansion valve Z0 refrigerant flows between the refrigerant flow path 9 and the internal space 30. Besides, the refrigerant flows through narrow clearances, namely, the needle fit/insert clearance 17, the engagement portion clearance 23, and the outer peripheral clearance 21. Consequently, sludge is likely to adhere to each of these clearances 17, 23, and 21.
If sludge adheres to the needle fit/insert clearance 17 and accumulates therein, this obstructs the movement of the needle 2, that is, the action of controlling the amount of refrigerant flow. On the other hand, if sludge adheres to the engagement portion clearance 23 and outer peripheral clearance 21 and accumulates thereon, this obstructs the operation of the rotor portion 10. Any of these cases results in undesirable incidents such as compressor abnormal liquid compression and compressor overheating.
Bearing in mind these problems, the present invention was made. Accordingly, an object of the present invention is to propose an electrically operated needle valve for a refrigerating circuit capable of preventing, as far as possible, the adhesion of sludge and a refrigerating system which is equipped with such an electrically operated needle valve.
The present invention employs the following concrete means with a view to providing solutions to the above-described problems.
An electrically operated needle valve for a refrigerating circuit according to a first invention of the present application is composed of a valve main body 1 including a needle fit/insert aperture 16 through which a needle 2 is slidably arranged and a refrigerant flow path 9 which is formed face to face with one end side of the needle fit/insert aperture 16 and whose flow path area is adjusted by the needle 2, and a casing 3 which is attached to the valve main body 1 with the other end side of the needle fit/insert aperture 16 positioned within an internal space 30 thereof and which houses in the internal space 30 at least a part of an electrically operated means X for driving the needle 2. And, the refrigerating circuit electrically operated needle valve of the first invention is characterized in that the valve main body 1 is provided with a refrigerant flow amount lowering means P for lowering the amount of flow of a refrigerant flowing into the internal space 30 from the refrigerant flow path 9 through a needle fit/insert clearance 17 formed between the needle fit/insert aperture 16 and the needle 2 inserted in the needle fit/insert aperture 16.
A second invention of the present application is characterized in that in the refrigerating circuit electrically operated needle valve according to the first invention the refrigerant flow amount lowering means P is a refrigerant flow path 41 which is formed in the valve main body 1 so as to establish, not through the needle fit/insert aperture 16, a communication between the refrigerant flow path 9 and the internal space 30.
A third invention of the present application is characterized in that in the refrigerating circuit electrically operated needle valve according to the first invention the needle fit/insert aperture 16 has a larger diameter aperture portion 16A located nearer to the refrigerant flow path 9 and a smaller diameter aperture portion 16B, located nearer to the electrically operated means X, for slidably supporting the needle 2, a pressure equalization aperture 18 is formed in the larger diameter aperture portion 16A, the pressure equalization aperture 18 being in communication, not through the smaller diameter aperture portion 16B, with the internal space 30, and the larger diameter aperture portion 16A and the pressure equalization aperture 18 together constitute the refrigerant flow amount lowering means P.
A fourth invention of the present application is characterized in that in the refrigerating circuit electrically operated needle valve according to the third invention the larger diameter aperture portion 16A is provided with a needle guide member 42 which, while slidable supporting the needle 2, allows refrigerant circulation in the axial direction of the larger diameter aperture portion 16A.
A fifth invention of the present application is characterized in that in the refrigerating circuit electrically operated needle valve according to the first invention the needle fit/insert aperture 16 has a first smaller diameter aperture portion 16C located nearer to the refrigerant flow path 9, a second smaller diameter aperture portion 16E located nearer to the electrically operated means X, and a larger diameter aperture portion 16D located midway between the first smaller diameter aperture portion 16C and the second smaller diameter aperture portion 16E and having a diameter greater than that of the first smaller diameter aperture portion 16C and an axial length longer than that of the first smaller diameter aperture portion 16C, the needle 2 is slidably supported either by the second smaller diameter aperture portion 16E or by both of the first smaller diameter aperture portion 16C and the second smaller diameter aperture portion 16E, and a pressure equalization aperture 18 is formed in the larger diameter aperture portion 16D, the pressure equalization aperture 18 being in communication, not through the second small diameter aperture portion 16E, with the internal space 30, and the larger diameter aperture portion 16D and the pressure equalization aperture 18 together constitute the refrigerant flow amount lowering means P.
A sixth invention of the present application is characterized in that in the refrigerating circuit, electrically operated needle valve according to the first invention the refrigerant flow amount lowering means P is implemented by a groove 43 (44) formed either in the outer peripheral surface of the needle 2 or in the inner peripheral surface of the needle fit/insert aperture 16.
A seventh invention of the present application is characterized in that in the refrigerating circuit electrically operated needle valve according to the third or fourth invention the valve main body 1 has a base portion 1A including the refrigerant flow path 9 and a secondary portion 1B which is a separated portion from the base portion 1A and the larger diameter aperture portion 16A is formed in the base portion 1A and the smaller diameter aperture portion 16B is formed in the secondary portion 1B.
An eighth invention of the present application is characterized in that in the refrigerating circuit electrically operated needle valve according to the fifth invention the valve main body 1 has a base portion 1A including the refrigerant flow path 9 and a secondary portion 1B which is a separated portion from the base portion 1A and the first smaller diameter aperture portion 16C and the larger diameter aperture portion 16D are formed in the base portion 1A whereas the second smaller diameter aperture portion 16E is formed in the secondary portion 1B.
A ninth invention of the present application is characterized in that in the refrigerating circuit electrically operated needle valve according to any one of the third to fifth inventions the pressure equalization aperture 18 is a round aperture and has an inside diameter of not less than 1.2 mm.
A tenth invention of the present application is characterized in that in the refrigerating circuit electrically operated needle valve according to the ninth invention a plurality of the pressure equalization apertures 18 are formed around the needle fit/insert aperture 16.
An eleventh invention of the present application is characterized in that in the refrigerating circuit electrically operated needle valve according to any one of the first to tenth inventions the clearance distance of the needle fit/insert clearance 17 is so set as to be not less than 0.2 mm.
An electrically operated needle valve for a refrigerating circuit according to a twelfth invention of the present application is composed of a valve main body 1 including a needle fit/insert aperture 16 through which a needle 2 is slidably arranged and a refrigerant flow path 9 which is formed face to face with one end side of the needle fit/insert aperture 16 and whose flow path area is adjusted by the needle 2, and a casing 3 which is attached to the valve main body 1 with the other end side of the needle fit/insert aperture 16 positioned within an internal space 30 thereof and which houses in the internal space 30 at least a part of an electrically operated means X for driving the needle 2, wherein the electrically operated means X is provided with a screw thread portion which engages on the axial outer side of the needle fit/insert aperture 16 and which extends in the axial direction of the needle fit/insert aperture 16 and an engagement clearance 23 thereof communicates with the needle fit/insert aperture 16 on the side of the other end of the needle fit/insert aperture 16. And, the refrigerating circuit electrically operated needle valve of the twelfth invention is characterized in that a refrigerant flow amount lowering means Q for lowering the amount of flow of a refrigerant flowing into the engagement clearance 23 from the refrigerant flow path 9 through the needle fit/insert aperture 16 is provided.
A thirteenth invention of the present application is characterized in that in the refrigerating circuit electrically operated needle valve according to the twelfth invention the refrigerant flow amount lowering means Q is a communicating aperture 45 which is formed fact to face with the other end of the needle fit/insert aperture 16 in the electrically operated means X.
A fourteenth invention of the present application is characterized in that in the refrigerating circuit electrically operated needle valve according to the twelfth invention the refrigerant flow amount lowering means Q is a refrigerant flow path 49 (50), formed in an end of the needle 2 fit and inserted in the needle fit/insert aperture 16, for bringing the needle fit/insert aperture 16 and the internal space 30 into communication with each other when the needle 2 makes, in its axial direction, a relative displacement with respect to the electrically operated means X.
An electrically operated needle valve for a refrigerating circuit according to a fifteenth invention is composed of a valve main body 1 including a needle fit/insert aperture 16 through which a needle 2 is slidably arranged and a refrigerant flow path 9 which is formed face to face with one end side of the needle fit/insert aperture 16 and whose flow path area is adjusted by the needle 2, and a casing 3 which is attached to the valve main body 1 with the other end side of the needle fit/insert aperture 16 positioned within an internal space 30 thereof and which houses in the internal space 30 at least a part of an electrically operated means X for driving the needle 2, wherein an outer peripheral clearance 21 is formed between the outer peripheral surface of the electrically operated means X and the inner peripheral surface of the casing 3. And, the refrigerating circuit electrically operated needle valve of the fifteenth invention is characterized in that a refrigerant flow amount lowering means R for lowering the amount of flow of a refrigerant flowing between a first space portion 31 of the internal space 30 located on one side of the electrically operated means X and a second space portion 32 of the internal space 30 located on the other side of the electrically operated means X through the outer peripheral clearance 21.
A sixteenth invention of the present application is characterized in that in the refrigerating circuit electrically operated needle valve according to the fifteenth invention the refrigerant flow amount lowering means R is a refrigerant flow path 46 which is formed through a peripheral wall area of a permanent magnet 4 of the electrically operated means X so that the refrigerant flow path 46 extends in the axial direction of the permanent magnet 4.
A seventeenth invention of the present application is characterized in that in the refrigerating circuit electrically operated needle valve according to the fifteenth invention the refrigerant flow amount lowering means R is a refrigerant flow path 47 which is formed through a peripheral wall area of a spacer 6, located on the inner peripheral side of a permanent magnet 4 of the electrically operated means X, for holding the permanent magnet 4 so that the refrigerant flow path 47 extends in the axial direction of the permanent magnet 4.
An eighteenth invention of the present application is characterized in that in the refrigerant circuit electrically operated needle valve according to the fifteenth invention the refrigerant flow amount lowering means R is a refrigerant flow path 48 which is formed at an abutting area between a permanent magnet 4 of the electrically operated means X and a spacer 6, located on the inner peripheral side of the permanent magnet 4, for holding the permanent magnet 4.
A nineteenth invention of the present application is characterized in that a refrigerating circuit electrically operated needle valve of any one of the first to eighteenth inventions is employed as an expansion valve.
A twentieth invention of the present application is characterized in that in the refrigerating system according to the nineteenth invention an HFC refrigerant or mixed refrigerant containing HFC, both of the refrigerants being of higher theoretical discharge temperature than that of R22, is used as the refrigerant.
A twenty-first invention of the present application is characterized in that in the refrigerating system according to the nineteenth invention an HFC refrigerant or mixed refrigerant containing HFC, both of the refrigerants being of higher theoretical discharge temperature than that of R12 and R502, is used as the refrigerant.
A twenty-second invention of the present application is characterized in that in the refrigerating system according to the nineteenth invention a single refrigerant of R32 or mixed refrigerant containing R32 is used as the refrigerant.
A twenty-third invention of the present application is characterized in that in the refrigerating system according to the nineteenth invention a synthetic oil is used as a refrigerating machine oil.
A twenty-fourth invention of the present application is characterized in that in the refrigerating system according to the twenty-second invention polyol ester, carbonic ester, polyvinyl ether, alkyne benzene, or polyalkylene glycol is used as a base oil of the synthetic oil.
A twenty-fifth invention of the present application is characterized in that in the refrigerating system of the twentieth or twenty-first invention a synthetic oil containing an extreme pressure additive is used as a refrigerating machine oil.
A twenty-sixth invention of the present application is characterized in that in the refrigerating system according to any one of the nineteenth to twenty-fifth inventions a plurality of utilization-side heat exchangers or heat source-side heat exchangers are provided.
The inventions of the present application provide the following effects.
The refrigerating circuit electrically operated needle valve according to the first invention includes a valve main body (1) having a needle fit/insert aperture (16) and a refrigerant flow path (9) to which one end of the needle fit/insert aperture (16) opens, a casing (3) attached to the valve main body (1), a needle (2), inserted in the needle fit/insert aperture (16), for adjusting the flow path area of the refrigerant flow path (9), and electrically operated means (X) for driving the needle (2). Further, the valve main body (1) on the other side of the needle fit/insert aperture (16) is positioned in an internal space (30) of the casing (3), while at least a part of the electrically operated means (X) is housed in the internal space (30) of the casing (3). Additionally, the valve main body (1) is provided with refrigerant flow amount lowering means (P) for lowering the amount of flow of a refrigerant flowing into the internal space (30) from the refrigerant flow path (9) through a needle fit/insert clearance (17) formed between the needle fit/insert aperture (16) and the needle (2).
Accordingly, when, with the rise or drop in refrigerant pressure on the upstream side of the electrically operated needle valve, a refrigerant flows through the needle fit/insert clearance 17, the amount of refrigerant flow in the needle fit/insert clearance 17 is lowered by the refrigerant flow amount lowering means P. By such a drop in refrigerant flow amount, the amount of adhesion of sludge included in the refrigerant to the wall surface of the needle fit/insert clearance 17 is reduced, thereby preventing, as far as possible, malfunction of the needle 2 due to sludge adhesion. This ensures that the needle 2 functions properly, and abnormal liquid compression or overheating in the compressor of the refrigerating circuit is forestalled, therefore achieving improved reliability.
In the refrigerating circuit electrically operated needle valve according to the second invention, the refrigerant flow amount lowering means (P) is a refrigerant flow path (41) which is formed in the valve main body (1) so as to establish another communication between the refrigerant flow path (9) and the internal space (30) independently of the needle fit/insert aperture (16).
Accordingly, the refrigerant flows mostly through the refrigerant flow path 41 of smaller path resistance, and the refrigerant flow amount of the needle fit/insert clearance 17 is reduced relatively, whereby, by such reduction, adhesion of sludge to the wall surface of the needle fit/insert clearance 17 can be suppressed. That is, the effect of the first invention can be accomplished without fail by a simple, inexpensive arrangement, i.e., by forming the refrigerant flow path 41.
In the refrigerating circuit electrically operated needle valve of the third invention according to the first invention, the needle fit/insert aperture (16) comprises a larger diameter aperture portion (16A) located nearer to the refrigerant flow path (9) and a smaller diameter aperture portion (16B), located nearer to the electrically operated means (X), for movably supporting the needle (2). Additionally, the refrigerant flow amount lowering means (P) is composed of a pressure equalization aperture (18) which is formed in the valve main body (1) so as to establish another communication between the larger diameter aperture portion (16A) and the internal space (30) independently of the smaller diameter aperture portion (16B), and the larger diameter aperture portion (16A).
In accordance with the refrigerating circuit electrically operated needle valve of the third invention, a region, located nearer to the refrigerant flow path 9 and corresponding to the larger diameter aperture portion 16A, of the needle fit/insert clearance 17 defined between the inner peripheral surface of the needle fit/insert aperture 16 and the outer peripheral surface of the needle 2, has a path area greater than that of a region corresponding to the smaller diameter aperture portion 16B, so that the former region is smaller in path resistance than that of the latter region, and in addition the pressure equalization aperture 18 is formed in the larger diameter aperture portion 16A.
As a result of such arrangement, the refrigerant from the refrigerant flow path 9 mostly flows into the internal space 30 from the region corresponding to the larger diameter aperture portion 16A through the pressure equalization aperture 18, and the amount of flow of a refrigerant flowing through the smaller diameter aperture portion 16B is reduced relatively. As a result, although a corresponding region of the needle fit/insert clearance 17 to the smaller diameter aperture portion 16B is a narrow clearance, the adhesion of sludge to the region is prevented as far as possible. That is, the effect of the first invention can be accomplished without fail by a simple, inexpensive arrangement, i.e., by forming the larger diameter aperture portion 16A and pressure equalization aperture 18.
In the refrigerating circuit electrically operated needle valve of the fourth invention according to the third invention, the larger diameter aperture portion (16A) is provided with a needle guide member (42) which, while movably supporting the needle (2), allows refrigerant circulation in the axial direction of the larger diameter aperture portion (16A).
Accordingly, while ensuring refrigerant circulation through the needle fit/insert clearance 17, the axial center of the needle 2 is held more assuredly by the needle guide member 42. As a result, the effect of the third invention is further speeded up.
In the refrigerating circuit electrically operated needle valve of the fifth invention according to the first invention, the needle fit/insert aperture (16) includes a first smaller diameter aperture portion (16C) located nearer to the refrigerant flow path (9), a second smaller diameter aperture portion (16E) located nearer to the electrically operated means (X), and a larger diameter aperture portion (16D) located between the first smaller diameter aperture portion (16C) and the second smaller diameter aperture portion (16E) and having a diameter greater than that of the first smaller diameter aperture portion (16C) and an axial length longer than that of the first smaller diameter aperture portion (16C). Further, the needle fit/insert aperture (16) is formed so as to movably support the needle (2) either by the second smaller diameter aperture portion (16E) or by both of the first smaller diameter aperture portion (16C) and the second smaller diameter aperture portion (16E). Additionally, the refrigerant flow amount lowering means (P) comprises a pressure equalization aperture (18) which is formed in valve main body (1) so as to establish another communication between the larger diameter aperture portion (16D) and the internal space (30) independently of the second smaller diameter aperture portion (16E), and the larger diameter aperture portion (16D).
In accordance with the refrigerating circuit electrically operated needle valve of the fifth invention, a region, located nearer to the refrigerant flow path 9 and corresponding to the larger diameter aperture portion 16A, of the needle fit/insert clearance 17 defined between the inner peripheral surface of the needle fit/insert aperture 16 and the outer peripheral surface of the needle 2 has a path area greater than that of regions corresponding to the first and second smaller diameter aperture portions 16C and 16E, so that the former region is smaller in path resistance than the latter regions. And, owing to the formation of the pressure equalization aperture 18 in the corresponding region to the larger diameter aperture portion 16A, the refrigerant flowing into the larger diameter aperture portion 16D from the refrigerant flow path 9 through the first smaller diameter aperture portion 16C flows into the internal space 30 from the larger diameter aperture portion 16D mostly through the pressure equalization aperture 18. As a result, the amount of flow of a refrigerant flowing through the second smaller diameter aperture portion 16E is relatively reduced, thereby preventing, as far as possible, the adhesion of sludge to the second smaller diameter aperture portion 16E. Further, although refrigerant flows through the first smaller diameter aperture portion 16C, its length is shorter in comparison with that of the larger diameter aperture portion 16D, so that the amount of sludge adhesion to such a portion is maintained small.
This introduces a synergistic effect which prevents, as far as possible, the operation of the needle 2 from being checked by adhered sludge, thereby ensuring that the needle 2 operates properly. Therefore the effect of the first invention is accomplished without fail.
In the refrigerating circuit electrically operated needle valve of the sixth invention according to the first invention, the refrigerant flow amount lowering means (P) is composed of a groove (43, 44) formed either in the outer peripheral surface of the needle (2) or in the inner peripheral surface of the needle fit/insert aperture (16).
Accordingly, when refrigerant flows through the needle fit/insert clearance 17 defined between the outer peripheral surface of the needle 2 and the inner peripheral surface of the needle fit/insert aperture 16, the refrigerant flows mostly through the groove 43 (44) of smaller path resistance. The refrigerant flow amount in narrow portions other than the groove 43 (44) is relatively reduced, and the adhesion of sludge onto the wall surface of the needle fit/insert clearance 17 is suppressed. That is, the effect of the first invention is achieved without fail by a simple, inexpensive arrangement, i.e., by forming the groove 43 (44).
In the refrigerating circuit electrically operated needle valve of the seventh invention according to the third or fourth invention, the valve main body (1) is composed of a base portion (1A) including the refrigerant flow path (9) and a secondary portion (1B) which is a separated portion from the base portion (1A) whereas the larger diameter aperture portion (16A) is formed in the base portion (1A) and the smaller diameter aperture portion (16B) is formed in the secondary portion (1B).
In the refrigerating circuit electrically operated needle valve of the eighth invention according to the fifth invention, the valve main body (1) comprises a base portion (1A) including the refrigerant flow path (9) and a secondary portion (1B) which is a separated portion from the base portion (1A) and the first smaller diameter aperture portion (16C) and the larger diameter aperture portion (16D) are formed in the base portion (1A) whereas the second smaller diameter aperture portion (16E) is formed in the secondary portion (1B).
In accordance with the refrigerating circuit electrically operated needle valves of the seventh and eighth inventions, in addition to being capable of obtaining the effects of the third to fifth inventions, for example the processing of each aperture portion is easier to carry out in comparison with forming the valve main body 1 in one piece, and it is possible to expect that the cost of manufacturing an electrically operated expansion valve is lowered.
In the refrigerating circuit electrically operated needle valve of the ninth invention according to any one of the third to fifth inventions, the pressure equalization aperture (18) is a round aperture and has an inside diameter of not less than 1.2 mm. Such arrangement ensures that the pressure equalization aperture 18 is nearly prevented from clogging due to sludge adhesion. As a result, the operation of pressure equalization by the pressure equalization aperture 18 is maintained well.
In the refrigerating circuit electrically operated needle valve of the tenth invention according to the ninth invention, a plurality of the pressure equalization apertures (18) are formed around the needle fit/insert aperture (16). Such arrangement further speeds up the operation of pressure equalization on the side of the refrigerating circuit electrically operated needle valve and allows the electrically operated needle valve to quickly shift to proper operation.
In the refrigerating circuit electrically operated needle valve of the eleventh invention according to any one of the first to sixth inventions, the clearance distance of the needle fit/insert clearance (17) is so set as to be not less than 0.2 mm. Such arrangement, while maintaining the action of holding the axial center of the needle 2 by the needle fit/insert aperture 16, makes it possible to effectively reduce the adhesion of sludge to the wall surface of the needle fit/insert clearance 17. This introduces a synergistic effect by which the needle 2 can be kept operating properly over a long period of time.
The refrigerating circuit electrically operated needle valve of the twelfth invention is composed of a valve main body (1) having a needle fit/insert aperture (16) and a refrigerant flow path (9) to which one end of the needle fit/insert aperture (16) opens, a casing (3) attached to the valve main body (1), a needle (2), inserted in the needle fit/insert aperture (16), for adjusting the flow path area of the refrigerant flow path (9), and electrically operated means (X) for driving the needle (2). Further, the valve main body (1) on the other side of the needle fit/insert aperture (16) is positioned in an internal space (30) of the casing (3), while at least a part of the electrically operated means (X) is housed in the internal space (30) of the casing (3). Further, the electrically operated means (X) is provided with a screw thread portion which engages with the valve main body (1) outside the needle fit/insert aperture (16) and extends in the axial direction of the needle fit/insert aperture (16) and an engagement clearance (23) between the screw thread portion of the electrically operated means (X) and the valve main body (1) communicates with one end of the needle fit/insert aperture (16). Additionally, a refrigerant flow amount lowering means (Q) for lowering the amount of flow of a refrigerant flowing into the engagement clearance (23) from the refrigerant flow path (9) through the needle fit/insert aperture (16) is provided.
Accordingly, when, with the rise or drop in refrigerant pressure on the upstream side of the electrically operated needle valve, refrigerant flows toward the engagement clearance 23 through the needle fit/insert clearance 17, the amount of flow of a refrigerant flowing into the engagement clearance 23 is lowered by the refrigerant flow amount lowering means Q. By such a drop in refrigerant flow amount, the amount of adhesion of sludge included in the refrigerant to the wall surface of the engagement clearance 23 is reduced, thereby preventing, as far as possible, malfunction of the screw thread portion due to sludge adhesion. This therefore ensures that the electrically operated means X functions properly, and abnormal liquid compression or overheating in the compressor of the refrigerating circuit is forestalled, therefore achieving improved reliability.
In the refrigerating circuit electrically operated needle valve of the thirteenth invention according to the twelfth invention, the refrigerant flow amount lowering means (Q) is a communicating aperture (45) which is formed fact to face with the other end of the needle fit/insert aperture (16) in the electrically operated means (X). Accordingly, refrigerant flowing into the side of the other end of the needle fit/insert aperture 16 through the needle fit/insert clearance 17 between the needle fit/insert aperture 16 and the needle 2 flows mostly through the communicating aperture 45 which is of smaller path resistance smaller than that of the engagement clearance 23. As a result, there occurs a relative drop in refrigerant flow amount in the engagement clearance 23, thereby reducing the adhesion of sludge to the wall surface of the engagement clearance 23. That is, in accordance with the thirteenth invention the effect of the twelfth invention can be achieved assuredly by a simple, inexpensive structure, i.e., by forming the communicating aperture 45.
In the refrigerating circuit electrically operated needle valve of the fourteenth invention according to the twelfth invention, the refrigerant flow amount lowering means (Q) is a refrigerant flow path (49, 50), formed in an end of the needle (2), for bringing the needle fit/insert aperture (16) and the internal space (30) into communication with each other when the needle (2) makes, in its axial direction, a relative displacement with respect to the electrically operated means (X).
Accordingly, when the needle 2 makes, in its axial direction, a relative displacement with respect to the electrically operated means X, i.e., when the needle 2 is placed in the valve closed state, refrigerant flowing into the side of the other end of the needle fit/insert aperture 16 through the needle fit/insert clearance 17 between the needle fit/insert aperture 16 and the needle 2 flows mostly through the refrigerant flow path 49 (50) which is of smaller path resistance than that of the engagement clearance 23. As a result, there occurs a relative drop in refrigerant flow amount in the engagement clearance 23, thereby reducing the adhesion of sludge to the wall surface of the engagement clearance 23. That is, in accordance with the fourteenth invention the effect of the twelfth invention can be achieved assuredly by a simple, inexpensive structure, i.e., by forming the refrigerant flow path 49 (50).
The refrigerating circuit electrically operated needle valve of the fifteenth invention includes a valve main body (1) having a needle fit/insert aperture (16) and a refrigerant flow path (9) to which one end of the needle fit/insert aperture (16) opens, a casing (3) attached to the valve main body (1), a needle (2), inserted in the needle fit/insert aperture (16), for adjusting the flow path area of the refrigerant flow path (9), and an electrically operated means (X) for driving the needle (2). Further, the valve main body (1) on the other side of the needle fit/insert aperture (16) is positioned in an internal space (30) of the casing (3), while at least a part of the electrically operated means (X) is housed in the internal space (30) of the casing (3). Furthermore, an outer peripheral clearance (21) is formed between the outer peripheral surface of the electrically operated means (X) and the inner peripheral surface of the casing (3). Additionally, a refrigerant flow amount lowering means (R) for lowering the amount of flow of a refrigerant flowing between a first space portion (31) of the internal space (30) located on one side of the electrically operated means (X) and a second space portion (32) of the internal space (30) located on the other side of the electrically operated means (X) through the outer peripheral clearance (21).
Accordingly, when, with the rise or drop in refrigerant pressure on the upstream side of the electrically operated needle valve, refrigerant flows between the first space portion 31 and the second space portion 32 through the outer peripheral clearance 21, the amount of flow of a refrigerant flowing into the outer peripheral clearance 21 is lowered by the refrigerant flow amount lowering means R. By such a drop in refrigerant flow amount, the amount of adhesion of sludge included in the refrigerant to the wall surface of the outer peripheral clearance 21 is reduced, thereby preventing, as far as possible, malfunction of the electrically operated means X due to sludge adhesion. This therefore ensures that the electrically operated means X functions properly, and abnormal liquid compression or overheating in the compressor of the refrigerating circuit is forestalled, therefore achieving improved reliability.
In the refrigerating circuit electrically operated needle valve of the sixteenth invention according to the fifteenth invention, the refrigerant flow amount lowering means (R) is a refrigerant flow path (46) formed in a peripheral wall area of a permanent magnet (4) of the electrically operated means (X).
Accordingly, refrigerant flowing between the first space portion 31 and the second space portion 32 flows mostly through the refrigerant flow path 46 which is of smaller path resistance than that of the outer peripheral clearance 21. As a result, there occurs a relative drop in refrigerant flow amount in the outer peripheral clearance 21, thereby reducing the adhesion of sludge to the wall surface of the outer peripheral clearance 21. That is, in accordance with the sixteenth invention the effect of the fifteenth invention can be achieved assuredly by a simple, inexpensive structure, i.e., by forming the refrigerant flow path 46.
In the refrigerating circuit electrically operated needle valve of the seventeenth invention according to the fifteenth invention, the refrigerant flow amount lowering means (R) is a refrigerant flow path (47) formed in a peripheral wall area of a spacer (6), located on the inner peripheral side of a permanent magnet (4) of the electrically operated means (X), for holding the permanent magnet (4).
Accordingly, refrigerant flowing between the first space portion 31 and the second space portion 32 flows mostly through the refrigerant flow path 47 which is of smaller path resistance than that of the outer peripheral clearance 21. As a result, there occurs a relative drop in refrigerant flow amount in the outer peripheral clearance 21, thereby reducing the adhesion of sludge to the wall surface of the outer peripheral clearance 21. That is, in accordance with the sixteenth invention the effect of the fifteenth invention can be achieved assuredly by a simple, inexpensive structure, i.e., by forming the refrigerant flow path 47.
In the refrigerating circuit electrically operated needle valve of the eighteenth invention according to the fifteenth invention, the refrigerant flow amount lowering means (R) is a refrigerant flow path (48) formed between a permanent magnet (4) of the electrically operated means (X) and a spacer (6), located on the inner peripheral side of the permanent magnet (4), for holding the permanent magnet (4).
Accordingly, refrigerant flowing between the first space portion 31 and the second space portion 32 flows mostly through the refrigerant flow path 48 which is of smaller path resistance than that of the outer peripheral clearance 21. As a result, there occurs a relative drop in refrigerant flow amount in the outer peripheral clearance 21, thereby reducing the adhesion of sludge to the wall surface of the outer peripheral clearance 21. That is, in accordance with the sixteenth invention the effect of the fifteenth invention can be achieved assuredly by a simple, inexpensive structure, i.e., by forming the refrigerant flow path 48.
The refrigerating system of the nineteenth invention employs, as an expansion valve, a refrigerating circuit electrically operated needle valve according to any one of the first to sixth and twelfth to eighteenth inventions.
Accordingly, the electrically operated needle valve has a structure capable of not easily failing to operate properly due to sludge adhesion. Even when the expansion valve is used in such a condition that sludge is relatively likely to be produced, its operation is maintained in a proper condition without malfunction due to sludge adhesion. As a result, the refrigerating system is improved in operation reliability.
In the refrigerating system of the twentieth invention according to the nineteenth invention, an HFC refrigerant or mixed refrigerant containing HFC, both of the refrigerants being of higher theoretical discharge temperature than that of R22, is used as the refrigerant.
In this case, sludge that is generated in the compressor has such a characteristic that the amount of sludge yield increases as the refrigerant discharge temperature goes up. Because of this, if an HFC refrigerant or a mixed refrigerant containing HFC, both of which being of higher theoretical discharge temperature than that of R22, is used as a refrigerant, this results in the increase in sludge yield amount itself. Accordingly, malfunctions due to sludge adhesion are likely to occur in the electrically operated valve.
However, even in such a case, the refrigerating system of this invention employs, as the electrically operated expansion valve, a refrigerating circuit electrically operated needle valve of any one of the first to sixth and twelfth to eighteenth inventions, therefore ensuring that the electrically operated expansion valve operates properly and proper operation of the refrigerating system is realized, although the refrigerant used produces much sludge due to its characteristic of high sludge yield.
In the refrigerating system of the twenty-first invention according to the nineteenth invention, either an HFC refrigerant or mixed refrigerant containing HFC which is of higher theoretical discharge temperature than that of R12 and R502 is used as the refrigerant.
In this case, sludge that is generated in the compressor has such a characteristic that the amount of sludge yield increases as the refrigerant discharge temperature goes up. Because of this, if an HFC refrigerant or a mixed refrigerant containing HFC, both of which being of higher theoretical discharge temperature than that of R12 and R502, is used as a refrigerant, this results in the increase in sludge yield amount itself. Accordingly, malfunctions due to sludge adhesion are likely to occur in the electrically operated valve.
However, even in such a case, the refrigerating system of this invention employs, as the electrically operated expansion valve, a refrigerating circuit electrically operated needle valve of any one of the first to sixth and twelfth to eighteenth inventions, therefore ensuring that the electrically operated expansion valve operates properly and proper operation of the refrigerating system is realized, although the refrigerant used produces much sludge due to its characteristic of high sludge yield.
In the refrigerating system of the twenty-second invention according to the nineteenth invention, a single refrigerant of R32 or mixed refrigerant containing R32 is used as the refrigerant.
In such a case, R32 has several advantages such as low global warming potential and high energy efficiency when used in refrigerating systems because of its high theoretical COP, high heat transfer rate, and low refrigerant pressure loss, but on the other hand R32 has some disadvantages such as high sludge yield because of its higher discharge temperature in comparison with R22 or the like.
However, even when the refrigerating system of this invention uses, as its refrigerant, a single refrigerant of R32 or R32-containing mixed refrigerant, it is possible to ensure proper operation of the electrically operated expansion valve although such a refrigerant produces much sludge, for a refrigerating circuit electrically operated needle valve according to any one of the first to sixth and twelfth to eighteenth inventions is used as the electrically operated expansion valve. This makes it possible to provide refrigerating systems of high global warming prevention effect.
In the refrigerating system of the twenty-third invention according to the nineteenth invention, a synthetic oil is used as a refrigerating machine oil. Further, in the refrigerating system according to the twenty-fourth invention, polyol ester, carbonic ester, polyvinyl ether, alkyne benzene, or polyalkylene glycol is used as a base oil of the synthetic oil.
In such a case, unlike, for example, mineral oil which is used as a refrigerating machine oil in an R22 refrigerating system, the aforesaid synthetic oil is composed of molecules having a molecular weight of narrow range and a nearly single structure. Because of this, the synthetic oil is susceptible to damage when undergoing chemical changes by the influence of moisture, air, impurities, or the like. Besides, such chemical damage results in the increase in sludge yield. Accordingly, in a refrigerating system employing such a synthetic oil as a refrigerating machine oil, the electrically operated expansion valve is likely to fail to operate properly by sludge adhesion.
However, even when the refrigerating system of this invention uses, as its refrigerating machine oil, a synthetic oil such as polyol ester, it is possible to ensure proper operation of the electrically operated expansion valve although such a refrigerating machine oil has a property of high sludge yield, for a refrigerating circuit electrically operated needle valve according to any one of the first to sixth and twelfth to eighteenth inventions is used as the electrically operated expansion valve, thereby making it possible to provide a refrigerating system of high operational reliability.
In the refrigerating system of the twenty-fifth invention according to the twentieth or twenty-first invention, a synthetic oil containing an extreme pressure additive is used as a refrigerating machine oil.
Generally, HFC refrigerant is inferior in self lubricity to HCFC refrigerant, which results in the requirement that an extreme pressure additive be added to refrigerating machine oil. However, such an extreme pressure additive reacts with iron at a high-temperature metallic sliding surface and changes to sludge. Because of this, when an HFC refrigerant is used and in addition a synthetic oil, to which an extreme pressure additive is added, is used as a refrigerating machine oil, the electrically operated expansion valve is liable to fail to operate properly due to sludge adhesion.
However, even when the refrigerating system of this invention uses, as its refrigerating machine oil, a synthetic oil containing an extreme pressure additive, it is possible to ensure proper operation of the electrically operated expansion valve although such a refrigerating machine oil has a property of high sludge yield, for a refrigerating circuit electrically operated needle valve according to any one of the first to sixth and twelfth to eighteenth inventions is used as the electrically operated expansion valve, thereby making it possible to provide a refrigerating system of high operational reliability.
The refrigerating system of the twenty-sixth invention according to any one of the nineteenth to twenty-fifth inventions is provided with a plurality of utilization-side heat exchangers or heat source-side heat exchangers.
In such a refrigerating system including a plurality of heat exchangers, the length of refrigerant piping is longer than for example a refrigerating system having a structure in which utilization-side heat exchangers and heat source-side heat exchangers are connected together on a one-for-one basis. Therefore, moisture, air, and impurities are present in larger amounts in the piping, and the probability that sludge is generated becomes higher because of the inclusion of such contaminant in the refrigerating circuit. Accordingly, in a refrigerating system including a plurality of utilization- or heat source-side heat exchangers, the malfunction of an electrically operated expansion valve is likely to be a problem.
However, even in such a case, a refrigerating circuit electrically operated needle valve having a structure hardly susceptible to sludge adhesion is used as an electrically operated expansion valve, as in the refrigerating system of any one of the nineteenth to twenty-fifth inventions, it is possible to provide a highly reliable refrigerating system free from the malfunction of the electrically operated expansion valve in spite of the structure including a plurality of heat exchangers and therefore having a lengthy piping length.